In progressive video scanning, successive scanning lines are vertically aligned from frame to frame. For example, in the 1080p/60 standard (1080 scanning lines per frame, 60 frames per second) line 1 of frame 2 is scanned at the same vertical location as is line 1 of frame 1, and so are lines 1 of frames 3, 4, etc.
An interlaced signal comprises a succession of even and odd fields, 2 successive fields making a frame. For example, in the 1080i/60 standard (1080 lines interlaced, 60 fields per second), each field is composed of 540 lines, and there are 60 fields or 30 frames per second. A frame comprises 1 even field and one odd field in succession. For interlaced video, line 1 of field 2 will be vertically located between line 1 and line 2 of field 1, and so will be line 1 of field 4, while line 1 of field 3 will be vertically co-incident with line 1 of field 1.
Interlaced video has been used since the early days of television, and has been slowly fallen into disfavor, and replaced by progressive scan for more and more applications, mostly because of the specific needs of computer or computer-like displays. More recent television displays such as LCDs or DLPs, can only be driven with a progressive scan. In these cases, interlaced signals have to be de-interlaced, which is costly and difficult.
The main advantage of interlaced signals is a reduction of the bandwidth requirements for a given resolution. The main inconvenience is the introduction of artifacts, which are particularly disturbing if the display de-interlacing process is mediocre or nonexistent. Examples types of artifacts may include inter-line tweeter or flicker, combing effects with motion, and potential field-to-field flicker.
It is desirable, therefore, to provide improved methods and systems of processing interlaced video that reduces the presence of artifacts.